Five-membered nitrogen-containing saturated heterocyclic compounds, e.g. pyrrolidone, are particularly useful as intermediates in the preparation of nylon-4 type polymers. These compounds are also useful in the preparation of n-methyl pyrrolidone and n-vinyl pyrrolidone which can be used as organic solvents.
The production of pyrrolidone from maleic anhydride is known. For example, U.S. Pat. No. 3,109,005, discloses a process wherein a mixture of maleic anhydride, dioxane and Raney nickel are charged to a reactor at a temperature of 250.degree. C. and a pressure of 200 atmospheres for about 10 hours. Moreover, Japanese Pat. No. 71/37,590 discloses a process wherein maleic anhydride is hydrogenated in dioxane at below 100.degree. C. at 145 atmospheres in the presence of a supported cobalt nickel catalyst. Ammonia is then added to the reaction vessel and the temperature is increased to 250.degree. C. to produce pyrrolidone.
The prior art methods for producing pyrrolidone are each disadvantageous for various reasons. First, these reactions required very high temperatures and pressures. Second, some of the prior art processes are two-step processes. Third, long reaction times are necessary. The instant process, on the other hand, can be conducted continuously in a single step at moderate temperatures and pressures to produce pyrrolidone from maleic anhydride. Furthermore, the instant process results in high yields and selectivities of pyrrolidone.